Vibration actuator and electronic equipment

ABSTRACT

A vibration actuator includes: a movable body including: a disk-shaped magnet; a pair of disk-shaped cores fixed on front and rear surfaces of the disk-shaped magnet and each having an opening at a center thereof; a pair of leaf springs having a substantially circular shape; and a pair of spring stopper weight parts each having one end positioned by joining the opening to be joined with one of the disk-shaped cores and having another end connected to a central part of one of the leaf springs; and a fixing body including an annular coil and configured to support and accommodate therein the movable body such that the disk-shaped magnet, the disk-shaped cores and the spring stopper weight parts are capable of vibrating in an axial direction inside the annular coil.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of U.S. patent application Ser. No.17/271,614 filed on Feb. 26, 2021, which is a National Phase of PCTPatent Application No. PCT/JP2019/033638 having International filingdate of Aug. 28, 2019, which claims the benefit of priority of JapanesePatent Application No. 2018-159790 filed on Aug. 28, 2018. The contentsof the above application are all incorporated by reference as if fullyset forth herein in their entirety.

TECHNICAL FIELD

The present invention relates to a vibration actuator and an electronicapparatus including the same.

BACKGROUND ART

Conventional electronic devices with a vibration function have vibrationactuators implemented as a source of vibration generation. By drivingthe vibration actuator and transmitting vibration to the user, theelectronic device can notify the user of incoming calls and improve thesense of operation and presence. Here, electronic devices includeportable game terminals, controllers (game pads) for stationary gamemachines, portable communication terminals such as cell phones andsmartphones, portable information terminals such as tablet PCs, andportable devices that can be carried by wearable terminals worn onclothes or arms.

As for vibration actuators with a structure that can be miniaturized tobe mounted on portable devices, for example, vibration actuators used inpagers and the like are known as disclosed in PTL 1.

In this vibration actuator, a pair of plate-like elastic bodies are madeto face each other and each is supported at the opening edge of acylindrical frame. Then, a yoke with a magnet attached is fixed to theraised central portion in one of the spiral-shaped plate elastic bodiesof the pair of plate elastic bodies, and the yoke is supported in theframe. The yoke constitutes a magnetic field generator together with themagnet, and a coil is placed in the magnetic field of this magneticfield generator with the coil attached to the other plate shaped elasticbody. The pair of plate elastic bodies are selectively resonated andvibrate by switching the current of different frequencies to this coilthrough an oscillation circuit, and the yoke vibrates in the frame inthe direction of the centerline of the frame.

In this vibration actuator, the distance between the magnet and the coiland between the yoke and the coil is larger than the distance betweenthe yoke and the inner wall of the frame. This prevents the yoke andmagnet from coming into contact with the coil and prevents the coil frombeing damaged by having the yoke collide with the inner peripheral wallof the frame first when it receives an external shock.

However, in practice, since the yoke with the magnet collides with theframe body, the pair of plate elastic bodies that elastically supportthe movable body with the yoke may be damaged by the impact.

For this reason, PTL 1 discloses, as a second embodiment, aconfiguration in which a fixing body is provided with a shaft on whichthe movable body slides and moves in the direction of vibration. As aresult, the yoke, which is a movable body, does not move to the innersurface of the frame by the shaft even if it receives an external shock,preventing it from colliding with the frame.

CITATION LIST Patent Literature

PTL 1

Japanese Patent Publication No. 3748637 SUMMARY OF INVENTION TechnicalProblem

However, in the conventional configuration of a vibration actuator inwhich a shaft on which a movable body slides is provided in a fixingbody, although the shaft can regulate the movement of the movable bodyand improve shock resistance, the movable body slides on the shaftduring driving, which may cause sliding noise.

The generation of noise due to contact, such as vibration noise,disadvantageously reduces the amplitude of the vibration actuatoritself. Therefore, it is desired that the vibration actuator, whichvibrates as a vibrating body by driving a movable body, should be ableto output vibration with high amplitude without vibration noise, andtransmit it to the user so that the user can fully experience thevibration, that is, output suitable vibration.

An object of the present invention is to provide a vibration actuatorand an electronic apparatus that generate suitable vibration with highoutput while achieving impact resistance.

Solution to Problem

A vibration actuator according to an embodiment of the present inventionincludes a fixing body including a coil; a movable body including amagnet disposed inside the coil in a radial direction such that themagnet is relatively movable in a vibration direction orthogonal to theradial direction, the movable body being configured to vibrate withrespect to the fixing body by cooperation of the magnet and the coil towhich power is fed; and an elastic support part configured to movablysupport the movable body with respect to the fixing body, wherein thefixing body includes a coil holding part disposed to surround themovable body and configured to hold the coil, wherein the coil holdingpart includes a coil protection wall part disposed on an inner diameterside of the coil with a space between the coil protection wall part andthe magnet, the coil protection wall part being configured to preventthe magnet and the coil from making contact with each other, wherein theelastic support part includes at least two or more leaf springs providedacross the coil holding part and the movable body to sandwich themovable body in the vibration direction, and wherein the leaf springssupport the movable body such that the movable body is movable in thevibration direction without making contact with the coil holding part ina non-vibration state and a vibration state of the movable body.

An electronic apparatus according to an embodiment of the presentinvention includes the vibration actuator having the above-mentionedconfiguration.

According to the present invention, it is possible to generate suitablevibration with high output while achieving impact resistance.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective view illustrating an external appearance of avibration actuator according to Embodiment 1 of the present invention;

FIG. 2 is a longitudinal sectional view illustrating a vibrationactuator according to Embodiment 1 of the present invention;

FIG. 3 is an exploded perspective view of the vibration actuator;

FIG. 4 is a perspective view illustrating a movable body and an elasticsupport part of the vibration actuator;

FIG. 5A and FIG. 5B illustrate a state where the elastic support partand the movable body are coupled with each other;

FIG. 6A and FIG. 6B illustrate a modification of the state where theelastic support part and the movable body are coupled with each other;

FIG. 7 is a plan view of the elastic support part including anattenuation part;

FIG. 8 is a partial sectional view of the elastic support part includingthe attenuation part;

FIG. 9 is a plan view of a modification of the elastic support partincluding the attenuation part;

FIG. 10 is a partial sectional view of a modification of the elasticsupport of the attenuation part;

FIG. 11 is a drawing schematically illustrating a magnetic circuitconfiguration of the vibration actuator;

FIG. 12 is a drawing schematically illustrating a balanced position of acoil and a magnet;

FIG. 13 is a drawing schematically illustrating a relative movement ofthe coil and the magnet;

FIG. 14 is a longitudinal sectional view illustrating a vibrationactuator according to Embodiment 2 of the present invention;

FIG. 15 is an exploded perspective view of the vibration actuatoraccording to Embodiment 2 of the present invention;

FIG. 16 is a drawing illustrating an example of an electronic apparatusin which the vibration actuator is mounted; and

FIG. 17 is a drawing illustrating an example of an electronic apparatusin which the vibration actuator is mounted.

DESCRIPTION OF EMBODIMENTS

Embodiments of the present invention will be elaborated below withreference to the accompanying drawings.

Embodiment 1 Overall Configuration of Vibration Actuator

FIG. 1 is a perspective view illustrating an external appearance of avibration actuator according to Embodiment 1 of the present invention,FIG. 2 is a longitudinal sectional view illustrating a vibrationactuator according to Embodiment 1 of the present invention, and FIG. 3is an exploded perspective view of the vibration actuator. In addition,FIG. 4 is a perspective view illustrating a movable body and an elasticsupport part of the vibration actuator. It is to be noted that in thepresent embodiment the “upper” side and the “lower” side are used forthe sake of convenience of description, and mean one side and the otherside in the vibration direction of movable body 20 in vibration actuator10. That is, when vibration actuator 10 is mounted in an electronicapparatus (see FIG. 16 and FIG. 17), the upper side and the lower sidemay be reversed, or may be set to the left side and the right side.

Vibration actuator 10 illustrated in FIG. 1 to FIG. 4 is mounted as avibration generation source in an electronic apparatus, or in otherwords, a mobile game terminal (for example, game controller GCillustrated in FIG. 16), or a mobile apparatus such as a smartphone (forexample, mobile terminal M illustrated in FIG. 17), and implements thevibration function of each apparatus. In addition, vibration actuator 10may have a function of generating a sound using vibration. Vibrationactuator 10 is driven when notifying incoming calls to the user, or whengiving a sense of control and realism to the user, for example.

As illustrated in FIG. 1, in vibration actuator 10 of the presentembodiment, movable body 20 (see FIG. 2) is housed in columnar fixingbody 50 such that it can be vibrated in the axis direction of thecolumn, and vibration actuator 10 itself serves as a vibrating memberwhen movable body 20 moves.

As illustrated in FIG. 2 to FIG. 4, vibration actuator 10 includesmovable body 20 including magnet 30 and movable body cores 41 and 42,fixing body 50 including coils 61 and 62, and plate-shaped elasticsupport parts 81 and 82 that reciprocally support movable body 20 withrespect to fixing body 50.

In vibration actuator 10, coils 61 and 62, magnet 30 and movable bodycores 41 and 42 constitute a magnetic circuit that vibrates movable body20. In vibration actuator 10, when coils 61 and 62 are energized bypower supplied by a power supply part (for example, drive control unit203 illustrated in FIG. 16 and FIG. 17), coils 61 and 62 and magnet 30operate in conjunction with each other, and movable body 20 reciprocatesin the vibration direction with respect to fixing body 50.

In vibration actuator 10 of the present embodiment, movable body 20inside coils 61 and 62 held by coil holding part 52 reciprocates in theaxis direction of coils 61 and 62, that is, the vibration direction. Tobe more specific, movable body 20 can reciprocate inside inner body part(coil protection wall part) 522 disposed between coils 61 and 62 andmovable body 20. Inner body part 522 is a part of coil holding part 52,and details of coil holding part 52 will be described later. Inaddition, the axis direction of coils 61 and 62 is the vibrationdirection of movable body 20, and the magnetization direction of magnet30 or the axis direction of coil holding part 52.

In vibration actuator 10, movable body 20 in the non-vibration statewhere it is not movable is disposed inside fixing body 50 (to be morespecific, inner body part 522 of coil holding part 52) with apredetermined distance therebetween through elastic support parts 81 and82 at the center of the length in the vibration direction of fixing body50 (to be more specific, coil holding part 52), and, in the directionorthogonal to the axis direction of movable body 20. Here, movable body20 is desirably located at a balanced position between coils 61 and 62so as not to make contact with inner body part 522 of coil holding part52. To be more specific, preferably, the center of the length of magnet30 and movable body cores 41 and 42 in the vibration direction isopposite to the center of the length between coils 61 and 62 in thevibration direction in the direction orthogonal to the vibrationdirection.

In the movable state (vibration state), movable body 20 reciprocates inthe vibration direction along inner peripheral surface 522 a of innerbody part 522. It is to be noted that a magnetic fluid may be interposedbetween inner body part 522 and movable body 20.

Movable Body 20

As illustrated in FIG. 2 to FIG. 4, inside cylindrical coil holding part52 of fixing body 50, movable body 20 is supported by elastic supportparts 81 and 82 such that movable body 20 can reciprocate along innerperipheral surface 522 a of inner body part 522. This reciprocationdirection is the direction in which the case (hereinafter referred to as“upper case”) 54 and the case (hereinafter referred to as “lower case”)56 for closing the opening of coil holding part 52 are opposite to eachother.

Movable body 20 includes magnet 30, movable body cores 41 and 42, andspring stoppers 22 and 24. In the present embodiment, from magnet 30 atthe center, movable body cores 41 and 42 and spring stoppers 22 and 24are continuously provided in the vibration direction. At movable body20, outer peripheral surface 20 a of magnet 30 and movable body cores 41and 42 is disposed inside inner peripheral surface 522 a of inner bodypart 522 with a predetermined distance therebetween.

When movable body 20 moves in the vibration direction, outer peripheralsurface 20 a reciprocates along inner peripheral surface 522 a withoutmaking contact therewith.

Radially inside coils 61 and 62, magnet 30 is disposed such that magnet30 can relatively move in the vibration direction orthogonal to theradial direction of coils 61 and 62. Radially inside coils 61 and 62,magnet 30 is disposed with a distance from coils 61 and 62. Here, the“radial direction” is a direction orthogonal to the axis of coils 61 and62 and is a direction orthogonal to the vibration direction. The“distance” in the radial direction is a distance between coils 61 and 62and magnet 30 including inner body part 522, and a distance with whichmovement can be made with no contact therebetween in the vibrationdirection of movable body 20. In the present embodiment, the distancebetween coils 61 and 62 and magnet 30 means the distance between theinner body part 522 on coils 61 and 62 side and magnet 30.

In addition, in the present embodiment, magnet 30 is disposed oppositeto the center of inner body part 522 outside the radial direction ofmagnet 30. It is to be noted that as long as magnet 30 is disposedinside the coils 61 and 62 such that two magnetization surfaces face theextending direction of the axis of coils 61 and 62, magnet 30 may have ashape other than a disk shape such as a cylindrical shape and a plateshape.

In the present embodiment, magnet 30 is a magnet having a disk shapewhose axis direction is the vibration direction and the magnetizationdirection. Desirably, the center of magnet 30 in the axis directioncoincides with the center of movable body 20 in the axis direction.

Magnet 30 is magnetized in the vibration direction, and front and rearsurfaces 30 a and 30 b separated in the vibration direction havedifferent polarities.

Movable body cores 41 and 42 are provided at front and rear surfaces 30a and 30 b of magnet 30, respectively.

Movable body cores 41 and 42 are magnetic substances, and constitute amagnetic circuit together with magnet 30 and coils 61 and 62 to functionas a yoke. Movable body cores 41 and 42 focus and efficiently transmitthe magnetic flux of magnet 30 without causing leakage so as toeffectively distribute the magnetic flux flowing between magnet 30 andcoils 61 and 62.

In addition, in addition to the function of a part of the magneticcircuit, movable body cores 41 and 42 have a function as the body ofmovable body 20 and a function as a weight, in movable body 20.

In the present embodiment, movable body cores 41 and 42 are formed in anannular plate shape and disposed such that the outer peripheral surfaceis flush with the outer peripheral surface of magnet 30 so as toconstitute outer peripheral surface 20 a of movable body 20 togetherwith the outer peripheral surface of magnet 30.

Movable body cores 41 and 42 are lamination cores and are formed bystacking silicon steel sheets, for example. In the present embodiment,movable body cores 41 and 42 are formed in the same manner, and aresymmetric about magnet 30. It is to be noted that movable body cores 41and 42 are attracted by magnet 30 and fixed to magnet 30 with a heatcurable adhesive agent such as epoxy resin or an anaerobic adhesiveagent, for example.

Openings 412 and 422 formed at center portions of movable body cores 41and 42 indicate the axis position of movable body 20 and serve asjoining parts with spring stoppers 22 and 24.

In the present embodiment, in the non-vibration state of movable body20, movable body cores 41 and 42 are disposed inside (radially inside)coils 61 and 62 so as to be opposite to coils 61 and 62 in the directionorthogonal to the axis direction of coils 61 and 62.

It is to be noted that together with magnet 30, movable body cores 41and 42 constitute the movable body side magnetic circuit part in themagnetic circuit.

Spring stoppers 22 and 24 have a function of fixing the movable bodyside magnetic circuit part to elastic support parts 81 and 82. Inaddition, spring stoppers 22 and 24 are weight parts that function as aweight of movable body 20 and increase the vibration output of movablebody 20.

In the present embodiment, spring stoppers 22 and 24 include joiningparts 222 and 242 joined to movable body cores 41 and 42, weight bodyparts 224 and 244, and spring fixing parts 226 and 246.

In the present embodiment, in spring stoppers 22 and 24, each of whichis formed in a cylindrical shape with a through hole that opens in thevibration direction, joining parts 222 and 242, weight body parts 224and 244 and spring fixing parts 226 and 246 are continuously provided inthe vibration direction. It is to be noted that a weight can beadditionally provided in the through hole, and then the through hole canhave a function as a weight adjusting part together with the weight. Byadditionally providing a weight in the through hole, the weight ofmovable body 20 can be increased to increase the vibration output ofmovable body 20.

Joining parts 222 and 242 are joined to movable body cores 41 and 42,respectively. To be more specific, joining parts 222 and 242 areinserted and internally fitted to openings 412 and 422 of movable bodycores 41 and 42, respectively. In openings 412 and 422, joining parts222 and 242 are fixed by bonding using a heat curable adhesive agentsuch as epoxy resin or an anaerobic adhesive agent, for example.

Weight body parts 224 and 244 are tube members having a larger outerdiameter and a larger mass than joining parts 222 and 242 and springfixing parts 226 and 246.

In addition, weight body parts 224 and 244 are provided at both endportions separated in the vibration direction in movable body 20, andare not provided at the outer periphery side of movable body 20. Withthis configuration, weight body parts 224 and 244 do no limit the coilinstallation space located at the outer periphery side of movable body20, and thus the electromagnetic conversion efficiency is not reduced.Thus, the weight of movable body 20 can be favorably increased, and thehigh vibration output can be achieved.

Spring fixing part 226 is joined to inner periphery part 802 (see FIG.4) serving as the inner diameter side end portion of the upper leafspring serving as elastic support part 81 at one end portion of thevibration direction of movable body 20, or in other words, the upper endportion of movable body 20. On the other hand, spring fixing part 246 isjoined to inner periphery part 802 (see FIG. 4) serving as the innerdiameter side end portion of the lower leaf spring serving as elasticsupport part 82 at the other end portion of in the vibration directionof the movable body, or in other words, the lower end portion of movablebody 20. It is to be noted that details of elastic support parts 81 and82 will be described later.

Spring fixing parts 226 and 246 protrude in the vibration direction fromweight body parts 224 and 244, and are joined at the ends thereof toinner periphery parts 802 and 802 of elastic support parts 81 and 82.Thus, elastic support parts 81 and 82 are fixed at the ends of springfixing parts 226 and 246 protruded from weight body parts 224 and 244 assteps from weight body parts 224 and 244. The steps ensure a clearanceas an elastic deformation region to the vibration direction for elasticsupport parts 81 and 82 protruding to the circumferentially outside frominner periphery parts 802 and 802.

Spring stoppers 22 and 24 may serve as a fixing part for fixing theweight or the spring. That is, each of spring stoppers 22 and 24 has afunction as weight and a spring fixation function of fixing elasticsupport parts 81 and 82, and thus it is not necessary to assemblemembers having such functions. By only providing spring stoppers 22 and24 to the movable body side magnetic circuit part, the upper leaf springand the lower leaf spring serving as elastic support parts 81 and 82 canbe readily mounted to movable body 20 having the weight function and thespring fixation function, and thus assemblability can be increased.

It is to be noted that spring stoppers 22 and 24 are desirably composedof a non-magnetic material while they may be composed of a magneticmaterial. With spring stoppers 22 and 24 composed of a non-magneticmaterial, the magnetic flux from movable body core 41 does not flowupward, and the magnetic flux from movable body core 42 does not flowdownward. Thus, the magnetic flux can efficiently flow toward coils 61and 62 located on the outer periphery side of movable body cores 41 and42.

In addition, preferably, spring stoppers 22 and 24 are formed of amaterial having a higher specific gravity (for example, a specificgravity of about 16 to 19) than a silicon steel sheet (the specificgravity of the steel sheet is 7.70 to 7.98) or the like. Examples of thematerial of spring stoppers 22 and 24 include tungsten. With thisconfiguration, even in the case where the size of the external shape ofmovable body 20 is set in design and the like, the mass of movable body20 can be relatively readily increased, and thus a desired vibrationoutput as a sufficient sensory vibration for the user can be achieved.

Fixing Body 50

Fixing body 50 supports movable body 20 through elastic support parts 81and 82 such that movable body 20 is movable in the vibration direction(the same direction as the coil axis direction and the magnetizationdirection) inside coils 61 and 62.

In the present embodiment, fixing body 50 includes, in addition to coils61 and 62, coil holding part 52, upper case (which may be referred to as“first case”) 54, lower case (which may be referred to as “second case”)56 and electromagnetic shield part 58.

Coil holding part 52 holds coils 61 and 62 disposed with a predetermineddistance therebetween in such a manner as to surround magnet 30, andguides the movement of movable body 20.

Coil holding part 52 is a cylindrical member formed with a resin or thelike, and is disposed radially inside coils 61 and 62. Coil holding part52 includes inner body part 522 interposed between coils 61 and 62 andmagnet 30. Inner body part 522 is disposed with a distance from magnet30 on the inner diameter side of coils 61 and 62. Inner body part 522prevents magnet 30 and coils 61 and 62 from making contact with eachother.

Coil holding part 52 includes, in addition to inner body part 522, outerbody part 524 as a concentric cylindrical member disposed to surroundthe outer periphery side of inner body part 522 with a spacetherebetween, and center annular part 526 that couples inner body part522 and outer body part 524.

Outer body part 524 is disposed to surround coils 61 and 62 disposed atthe outer peripheral surface of inner body part 522, and the outerperipheral surface of outer body part 524 is covered with cylindricalelectromagnetic shield part 58. The opening both end portions (upper andlower end portions) of outer body part 524 sandwich the outer peripherypart 806 of elastic support parts 81 and 82 together with upper andlower cases 54 and 56, and are closed with upper and lower cases 54 and56. By closing the both ends of outer body part 524 with upper and lowercases 54 and 56, a hollow vibration actuator housing is formed.

Center annular part 526 has a disk shape provided between inner bodypart 522 and outer body part 524 at the center in the axis direction(the vibration direction).

That is, in coil holding part 52, outer body part 524, inner body part522 and center annular part 526 form pockets (coil insertion parts)recessed in the cross-section with circular openings at both ends in theaxis direction. Center annular part 526 forms the bottom portion of thepocket. Coils 61 and 62 are housed and fixed in the recessed pockets.

Inner body part 522 is a cylindrical member that is disposed such thatmovable body 20 can reciprocate in the axis direction on the innerperiphery side, and coils 61 and 62 are disposed side by side in theaxis direction (coil axis direction) to surround the outer peripheralsurface of inner body part 522.

Inner peripheral surface 522 a of inner body part 522 is disposedopposite to the outer peripheral surface of movable body 20 with apredetermined distance therebetween. With this predetermined distance,movable body 20 can move in the axis direction as the vibrationdirection without making contact with inner peripheral surface 522 a.Movable body 20 moves along inner peripheral surface 522 a withoutmaking contact therewith.

The thickness of inner body part 522 is preferably smaller than thethickness of outer body part 524, and has a strength with which outercircumference side coils 61 and 62 are not affected even when movingmovable body 20 makes contact therewith. That is, the durability as coilholding part 52 that holds coils 61 and 62 is ensured mainly by thethickness of inner body part 522 in the radial direction, the axiallength of center annular part 526, and the thickness of outer body part524 in the radial direction.

It is to be noted that with coil holding part 52, a coil line thatcouples coils 61 and 62 spaced from each other in the axis direction isprovided in coil holding part 52, and is guided by a guide groove(omitted in the drawing) communicating between the pockets (slits)having the recessed cross-sectional shapes. Coils 61 and 62 are turnedat coil connecting part 521 at the lower portion of coil holding part 52and connected to the outside. Coil connecting part 521 is located onprotrusion 564 of lower case 56. It is to be noted that the guide grooveis provided at the outer periphery part of center annular part 526, forexample.

In coil holding part 52, coils 61 and 62 are inserted to the pockets(slits) formed by inner body part 522, outer body part 524 and centerannular part 526 with a recessed cross-sectional shape with openings onboth sides in the axis direction, and coils 61 and 62 are fixed bybonding or sealing. In the present embodiment, coils 61 and 62 are fixedby bonding to all of the inner body part 522, outer body part 524 andcenter annular part 526. Thus, coils 61 and 62 can increase the joiningstrength with coil holding part 52, and even in the case where a largeimpact is applied, the damage to coils 61 and 62 is reduced incomparison with a configuration in which the movable body directly makescontact with the coil.

In vibration actuator 10, coils 61 and 62 vibrate in the axis directionof coils 61 and 62 (the magnetization direction of magnet 30), and areused for generating the driving source of vibration actuator 10 togetherwith magnet 30 and movable body cores 41 and 42. Coils 61 and 62 areenergized at the time of driving, and constitutes the voice coil motortogether with magnet 30.

In the present embodiment, coils 61 and 62 are composed of self-weldingline coils. With this configuration, in mounting to coil holding part52, it can be inserted and held in the slit pocket having a recessedcross-sectional shape while maintaining the cylindrical shape.Therefore, the coil line will not be untied, and thus assemblability ofvibration actuator 10 can be improved.

Preferably, the coil axis of coils 61 and 62 is disposed coaxially withthe axis of coil holding part 52 or the axis of magnet 30.

Coils 61 and 62 are held by coil holding part 52 such that the center ofthe length in the coil axis direction (the vibration direction) islocated at substantially the same (or the same) location in thevibration direction as the center of the length in the vibrationdirection of movable body 20 (to be more specific, the vibrationdirection of magnet 30). It is to be noted that coils 61 and 62 of thepresent embodiment are wound in opposite directions such that currentflows in opposite directions upon energization.

The both end portions of coils 61 and 62 are connected to the powersupply part (for example, drive control unit 203 illustrated in FIG. 16and FIG. 17). For example, the both end portions of coils 61 and 62 areconnected to the alternating current supply part, and alternatingcurrent power source (AC voltage) is supplied from the alternatingcurrent supply part to coils 61 and 62. With this configuration, withthe magnet, coils 61 and 62 can generate a thrust for movement in thecontacting or separating direction in the respective axis directions.

In the case where in magnet 30, surface 30 a side on one side (in thepresent embodiment, the upper side) in the magnetization direction ismagnetized to the N pole and rear surface 30 b side on the other side(in the present embodiment, the lower side) in the magnetizationdirection is magnetized to the S pole, a magnetic flux radiated frommovable body core 41 on surface 30 a side of magnet 30 to movable bodycore 42 of rear surface 30 b side of magnet 30 is formed. To be morespecific, the magnetic flux flows such that the magnetic flux is emittedfrom the surface side of magnet 30 and radiated from movable body core41 on the upper side of magnet 30 to coil 61 side, so as to impinge onmagnet 30 from movable body core 42 on the lower side of magnet 30through electromagnetic shield part 58 and coil 62. In this manner, themagnetic flux radially traverses coils 61 and 62 at any portion of coils61 and 62 disposed to surround magnet 30 and movable body cores 41 and42. With this configuration, when coils 61 and 62 are energized, theLorentz force acts in the same direction (for example, the −F directionillustrated in FIG. 11) along the magnetization direction.

Upper case 54 and lower case 56 are formed in bottomed cylindricalshapes, and bottom portions 541 and 561 constitute the top surface andbottom surface of vibration actuator 10 of the present embodiment. It isto be noted that upper case 54 and lower case 56 may be recessed metalplates formed by drawing.

Electromagnetic shield part 58 is a cylindrical magnetic substancedisposed to cover the outer periphery of coil holding part 52.Electromagnetic shield part 58 functions as an electromagnetic shield,and prevents leakage of the magnetic flux to the outside of vibrationactuator 10. With this electromagnetic shield effect of electromagneticshield part 58, leakage of the magnetic flux to the outside of thevibration actuator can be reduced.

In addition, together with coils 61 and 62, magnet 30, and movable bodycores 41 and 42, electromagnetic shield part 58 also functions as themagnetic circuit, and thus the electromagnetic conversion efficiency canbe increased by increasing the thrust constant. Electromagnetic shieldpart 58 functions as a magnetic spring together with magnet 30 byutilizing the magnetic attractive force of magnet 30.

Inside electromagnetic shield part 58, the center of the length ofelectromagnetic shield part 58 in the vibration direction is located atthe center of vibration direction of magnet 30. With this configuration,as illustrated in FIG. 12, magnetic attractive force F1 acts betweenmagnet 30 and electromagnetic shield part 58 in the non-driving state.Thus, as illustrated in FIG. 13, even when movable body 20 excessivelymoves to one side in the vibration direction, magnetic attractive forceF2 is generated between magnet 30 and electromagnetic shield part 58,and movable body 20 is returned to the original position with the forceof thrust F3.

The total spring constant is the sum of the spring constant of the leafspring as elastic support parts 81 and 82 and the spring constant of themagnetic spring of magnet 30 and electromagnetic shield part 58. Withthis configuration, the spring constant of the leaf spring can bereduced. As a result, the stress of the leaf spring is reduced and thenegative influence on the lifetime is suppressed. In this manner, thereliability of vibration actuator 10 can be increased.

Bottom portion 541 of upper case 54 and bottom portion 561 of lower case56 are disk-shaped members, and circumferentially extended annular stepparts are provided at a position closer to bottom portions 541 and 561than the opening edge inside cylindrical peripheral wall parts 542 and562 that rise from the outer peripheral edges of bottom portions 541 and561 (see FIG. 2).

It is to be noted that in the present embodiment, the outer surfaces ofperipheral wall parts 542 and 562 are flush with the outer surface ofelectromagnetic shield part 58 surrounding coils 61 and 62. With thisconfiguration, vibration actuator 10 is formed in a small and simplesubstantially columnar shape (barrel shape) with a flat outer peripheralsurface, and thus its installation space can be formed in a simplecolumnar shape.

Upper case 54 and lower case 56 are fitted with the opening edge partsof coil holding part 52 at the step parts, and sandwich and fix outerperiphery parts 806 of elastic support parts 81 and 82 with the openingedge parts. The length from the bottom portions 541 and 561 to the steppart can be defined by the movable range of movable body 20. The movablerange of movable body 20 is set such that movable body 20 vibrateswithin the movable range with deformation of elastic support parts 81and 82.

Upper case 54 and lower case 56 of fixing body 50 have a function as amovable range suppressing mechanism serving as hard stop (movable rangelimitation) HS through the movable body space with the length frombottom portions 541 and 561 to the step part where elastic support parts81 and 82 are fixed. That is, the movable body space is defined in alength range within which plastic deformation of elastic support parts81 and 82 does not occur. With this configuration, even when a forceexceeding the movable range is exerted on movable body 20, elasticsupport parts 81 and 82 make contact with fixing body 50 with no plasticdeformation. Thus, elastic support parts 81 and 82 are not damaged andthe reliability can be increased.

Elastic Support Parts 81 and 82

Elastic support parts 81 and 82 are provided across movable body 20 andfixing body 50 in a direction orthogonal to the vibration direction insuch a manner as to sandwich movable body 20 in the vibration directionof movable body 20, and to support movable body 20 with respect tofixing body 50 such that movable body 20 can reciprocate in thevibration direction.

In the present embodiment, as illustrated in FIG. 2 to FIG. 4, elasticsupport parts 81 and 82 are connected to fixing body 50 at the endportions separated in the vibration direction in movable body 20.

In elastic support parts 81 and 82, inner periphery part 802 is fit tothe end portions (spring fixing parts 226 and 246) separated in the axisdirection (the vibration direction) of movable body 20 and thus it isattached to movable body 20 such that outer periphery part 806 side ison the radially outside.

Elastic support parts 81 and 82 support movable body 20 such thatmovable body 20 does not make contact with fixing body 50 when movablebody 20 is in the non-vibration state and the vibration state. It is tobe noted that with elastic support parts 81 and 82, even when movablebody 20 makes contact with inner peripheral surface 522 a of inner bodypart 522 at the time of driving, magnetic circuits, or to be morespecific, coils 61 and 62 are not damaged. Elastic support parts 81 and82 may be composed of any member as long as movable body 20 is movablyelastically supported.

Elastic support parts 81 and 82 may be composed of non-magneticsubstances, or magnetic substances (to be more specific, ferromagneticsubstances). In the case where elastic support parts 81 and 82 arecomposed of a non-magnetic substance leaf spring, stainless-steel sheetsof SUS304, SUS316 or the like may be used. In addition, in the casewhere elastic support parts 81 and 82 are composed of a magneticsubstance, stainless-steel sheets of SUS301 and the like are applicable.

In the case where elastic support parts 81 and 82 are disposed atpositions where the influence of the magnetic field of the magneticcircuit in movable body 20 is small in a vibration actuator, thematerial of elastic support parts 81 and 82 may be a non-magneticmaterial, or a magnetic material. In addition, in the case where elasticsupport parts 81 and 82 are disposed at position where the influence ofthe magnetic field of the magnetic circuit in movable body 20 is large,elastic support parts 81 and 82 are preferably composed of anon-magnetic material as non-magnetic substances.

As an example of the material of elastic support parts 81 and 82, it isknown that magnetic materials (such as SUS301) have higher durabilityand less inexpensive than non-magnetic materials (such as SUS304 andSUS316).

In vibration actuator 10 of the present embodiment, elastic supportparts 81 and 82 are disposed at positions where the influence of themagnetic field of the magnetic circuit in movable body 20 is small, andtherefore, for example, a magnetic material (ferromagnetic material)such as SUS301 is used as the material of elastic support parts 81 and82. In this manner, in the present embodiment, elastic support parts 81and 82 have a higher durability and are less expensive in comparisonwith the case where a non-magnetic material is used, and it is thuspossible to achieve vibration actuator 10 having excellent durabilitywith a reduced cost.

As illustrated in FIG. 4, elastic support parts 81 and 82 are composedof a plurality of planar leaf springs. In movable body 20, elasticsupport parts 81 and 82 may be composed of three or more leaf springs.Such a plurality of leaf springs is attached along the directionorthogonal to the vibration direction.

Elastic support parts 81 and 82 serving as leaf springs have shapes inwhich annular inner periphery part 802 serving as an inner spring endportion and outer periphery part 806 serving as an outer spring endportion are joined with elastically deformable arc-like deformation arm804. When deformation arm 804 is deformed, inner periphery part 802 andouter periphery part 806 are relatively displaced with respect to theaxis direction.

In elastic support parts 81 and 82, outer periphery part 806 is joinedto fixing body 50, and inner periphery part 802 is joined to movablebody 20.

In the present embodiment, the leaf springs as elastic support parts 81and 82 are formed by metal working using a stainless-steel sheet, or tobe more specific, elastic support parts 81 and 82 are thin tabulardisc-shaped spiral springs. Since elastic support parts 81 and 82 haveplate shapes, the positional accuracy can be improved, that is, theworking accuracy can be improved in comparison with a spring of a coneshape.

In the present embodiment, in the plurality of elastic support parts 81and 82 with the same spiral direction, outer periphery part 806 servingas one end of the outer circumference side is fixed to fixing body 50,and inner periphery part 802 serving as the other end of inner peripheryside is fixed to movable body 20.

As described above, in the present embodiment, as the plurality ofelastic support parts 81 and 82, a plurality of spiral leaf springs isattached to the end portions separated in the vibration direction inmovable body 20. With this configuration, in vibration actuator 10, inthe case where movable body 20 is elastically supported with respect tofixing body 50, as the movement amount of movable body 20 is increased,movable body 20 moves in the lateral direction (here, the direction on aplane perpendicular to the vibration direction) while being slightlyrotated. If the plurality of leaf springs has the opposite spiraldirections, the plurality of leaf springs moves in the compressingdirection or the pulling direction, and smooth movement is hampered.

Elastic support parts 81 and 82 of the present embodiment are fixed tomovable body 20 such that the spiral directions are the same, andtherefore even when the movement amount of movable body 20 is large,smooth movement, or in other words, deformation, can be achieved. Thus,a large amplitude can be achieved and the vibration output can beincreased.

Elastic support parts 81 and 82 are fixed to the ends of spring fixingparts 226 and 246 protruding to form steps at the outer periphery partfrom weight body parts 224 and 244 at the end portions in movable body20 separated in the vibration direction (in the present embodiment, thevertical direction) of movable body 20. Elastic support parts 81 and 82are disposed to extend in the direction orthogonal to the vibrationdirection from the ends of spring fixing parts 226 and 246, and thus thestep ensures the elastic deformation region. In this manner, the elasticsupport part can be created with a reduced cost, and the reliability ofthe vibration actuator itself using the same can be improved.

In the present embodiment, elastic support parts 81 and 82 and movablebody 20 are firmly joined through fixation pins 26 and 28 such that theyare not dropped due to the vibration of movable body 20.

Fixation pins 26 and 28 illustrated in FIG. 2 to FIG. 4 include flanges264 and 284 at opening edge parts of cylindrical pin bodies 262 and 282that can be press fit to spring fixing parts 226 and 246.

FIG. 5A and FIG. 5B are drawings illustrating a coupling state ofelastic support parts 81 and 82 and movable body 20.

As illustrated in FIG. 5A, when plate-shaped elastic support parts 81and 82 are fixed to movable body 20, inner periphery parts 802 ofelastic support parts 81 and 82 is placed on spring fixing parts 226 and246 serving as the end portions of vibration direction of movable body20. Next, pin bodies 262 and 282 of fixation pins 26 and 28 are pressedinto the through holes that open at spring fixing parts 226 and 246through the openings of inner periphery parts 802 and 802 ofplate-shaped elastic support parts 81 and 82.

With this configuration, as illustrated in FIG. 5B, with spring fixingparts 226 and 246, flanges 264 and 284 sandwich inner periphery parts802 of elastic support parts 81 and 82, and elastic support parts 81 and82 are firmly joined to spring fixing parts 226 and 246.

When movable body 20 is reciprocated, no dropping occurs even when alarge force is applied to spring fixing parts 226 and 246. In addition,for example, it is more resistant to repetitive vibration in comparisonwith the case where fixation is achieved by bonding alone.

In addition, inner periphery parts 802 of elastic support parts 81 and82 and spring fixing parts 226 and 246 may be joined by welding, bond,swaging or the like, or still alternatively, they may be joined by acombination of welding, bond, and swaging.

FIG. 6A and FIG. 6B are drawings illustrating a modification of acoupling state of elastic support parts 81 and 82 and movable body 20.

In comparison with the configuration of movable body 20, in movable body20 illustrated in FIG. 6A and FIG. 6B, spring fixing parts 226 and 246of spring stoppers 22A and 24A having a similar configuration as springstoppers 22 and 24 include cylindrical swaging parts 228 and 248protruding from the peripheries of the through holes that open to thevibration direction.

As illustrated in FIG. 6A, swaging parts 228 and 248 are inserted to theopenings of inner periphery parts 802 of elastic support parts 81 and82. Desirably, the outer periphery of cylindrical swaging parts 228 and248 has a diameter that internally fitted to inner periphery part 802 ofelastic support parts 81 and 82. In addition, the protrusion length ofswaging parts 228 and 248 from the surface where inner periphery part802 is placed is greater than the thickness of elastic support parts 81and 82.

As illustrated in FIG. 6A, by inserting inner periphery parts 802 and802 to swaging parts 228 and 248 and crushing swaging parts 228 and 248for swaging, elastic support parts 81 and 82 and spring fixing parts 226and 246 are firmly joined to each other. This configuration can reducethe number of components and man hours for assembly, and thus canincrease the productivity in comparison with the configurationillustrated in FIG. 5 in which fixation pins 26 and 28 are used. Inaddition, the joining of elastic support parts 81 and 82 and springfixing parts 226 and 246 can be achieved through welding or bonding, inaddition to swaging.

On the other hand, as described above with FIG. 2, outer periphery part806 of elastic support part 81 is fixed, on the outside in the radialdirection, to fixing body 50 by being sandwiched between inner peripheryportion the opening (the step part of the inner periphery side) ofperipheral wall part 542 of upper case 54 and the opening edge of outerbody part 524 of coil holding part 52.

As illustrated in FIG. 2, outer periphery part 806 of elastic supportpart 82 is fixed, on the outside in the radial direction, to fixing body50 by being sandwiched between the opening edge of outer body part 524of coil holding part 52 and the step part inside the opening ofperipheral wall part 562 of lower case 56.

In this manner, between the upper and lower opening edges of outer bodypart 524 of coil holding part 52 and upper and lower cases 54 and 56that close the opening edges by being fit thereto, elastic support parts81 and 82 are sandwiched in the state where they are disposed in thedirection orthogonal to the vibration direction.

In the present embodiment, in elastic support parts 81 and 82,attenuation part (damper) 72 serving as an attenuation means forattenuating the vibration generated at elastic support parts 81 and 82is attached to deformation arm 804 or to deformation arm 804 and outerperiphery part 806. In elastic support parts 81 and 82, the attenuationmeans suppresses the resonance peak, and generates stable vibration overa wide range.

FIG. 7 is a plan view of elastic support part 81 including anattenuation part, and FIG. 8 is a partial sectional view of the elasticsupport part of attenuation part 72. It is to be noted that whileelastic support part 82 also includes attenuation part 72, elasticsupport part 82 has a configuration similar to that of elastic supportpart 81, and therefore the description thereof is omitted.

As illustrated in FIG. 7 and FIG. 8, attenuation part 72 of the presentembodiment is an elastic member of an elastomer having H-cross-sectionalshape or the like in which center portions of a pair of opposite flanges722 disposed in parallel with each other are coupled with rib (pushingpart) 724. Attenuation part 72 is disposed by inserting an elastomer tothe bridge portion of elastic support part 81 serving as a leaf spring,which is between outer periphery part 806 and deformation arm 804 in thepresent embodiment, such that it makes contact therewith. A plurality ofattenuation parts 72 are attached to elastic support part 81 withoutbeing firmly fixed thereto.

Attenuation part 72 serving as the attenuation means attenuates a sharpspring resonance at elastic support part 81 and prevents a largevibration difference among the frequencies due to the vibrationsignificantly increased near the resonance frequency. With thisconfiguration, before plastic deformation, movable body 20 vibrateswithout making contact with bottom portions 541 and 561, and causes noabnormal noise due to the contact.

The shape, material and the like of attenuation part 72 are not limitedas long as the generation of shape vibration at elastic support part 81(82) can be prevented. FIG. 9 and FIG. 10 are plan views and partialsectional views of an elastic support part including attenuation part72A as a modification.

Attenuation part 72A illustrated in FIG. 9 and FIG. 10 is an elastomerhaving a T-cross-sectional shape, and includes plate-shaped flange 722and pushing part 724A protruding from the center portion of flange 722.

In attenuation part 72A, pushing part 724A is inserted from the onesurface side of elastic support part 81 to the area between springportions, or to be more specific, the area between outer periphery part806 and deformation arm 804 such that flange 722 is provided as a bridgebetween the spring portions. Attaching portion 73 is an ultravioletcurable resin, an adhesive agent that is not firmly fixed to elasticsupport part 81 or the like, and is fixed to pushing part 724A with ashape with which pushing part 724A is not dropped from the area betweenthe spring portions on the rear surface side of elastic support part 81.

With this configuration, attenuation part 72A can reduce the componentcosts in comparison with attenuation part 72 having theH-cross-sectional shape, can achieve an attenuation effect comparable tothat of attenuation part 72 to suppress the resonance peak, and cangenerate stable vibration over a wide range.

That is, in vibration actuator 10, it can be said that movable body 20corresponds to the mass part of a vibration model of a spring-masssystem, and thus the sharp peak is suppressed by attenuating thevibration when there is a sharp resonance (sharp peak). By attenuatingthe vibration, the sharp resonance is eliminated, and vibration of asuitable and stable maximum movement amount is output with no unevennessof the maximum amplitude value and the maximum movement amount ofmovable body 20 at resonance.

In vibration actuator 10, the magnetic circuit illustrated in FIG. 11 isformed. In addition, in vibration actuator 10, coils 61 and 62 aredisposed such that the coil axis is orthogonal to the magnetic flux ofmovable body cores 41 and 42 sandwiching magnet 30 in the vibrationdirection. Accordingly, as illustrated in FIG. 11, when coils 61 and 62are energized, a Lorentz force in the −F direction is generated at coils61 and 62 in accordance with Fleming's left hand rule with theinteraction between the magnetic field of magnet 30 and the currentflowing through coils 61 and 62.

The Lorentz force in the −F direction is in the direction orthogonal tothe magnetic field direction and the direction of the current flowingthrough coils 61 and 62. Since coils 61 and 62 are fixed to fixing body50 (coil holding part 52), a force opposite to the Lorentz force in the−F direction is generated as a thrust of an F direction at movable body20 including magnet 30 in accordance with the action-reaction law. Withthis configuration, movable body 20 including magnet 30 moves to the Fdirection, or in other words, to bottom portion 541 side of upper case54.

In addition, when the energization direction of coils 61 and 62 isswitched to the opposite direction and coils 61 and 62 are energized,the Lorentz force of the opposite F direction is generated. When theLorentz force of the F direction is generated, the force opposite to theLorentz force of the F direction is generated at movable body 20 as athrust (a thrust of the F direction) in accordance with theaction-reaction law. As a result, movable body 20 move to the −Fdirection, or in other words, to lower case 56 side of bottom portion561 of fixing body 50.

Vibration actuator 10 includes fixing body 50 including coils 61 and 62,movable body 20 including magnet 30 that is magnetized in the axisdirection of coils 61 and 62 and disposed radially inside of coils 61and 62, and plate-shaped elastic support parts 81 and 82 thatelastically hold movable body 20 such that movable body 20 is movable inthe vibration direction.

In addition, inner body part 522 is provided between coils 61 and 62 andouter peripheral surface 30 a of movable body 20, and elastic supportparts 81 and 82 support movable body 20 such that they do not makecontact with each other when movable body 20 is in the non-vibrationstate and the vibration state.

With this configuration, with respect to fixing body 50, movable body 20is supported with a gap from inner body part 522 in the non-vibrationstate with no movement and in the vibration state with movement, andthus movable body 20 does not make contact with fixing body 50 when itis moving, or in other words, vibrating.

In addition, for example, when vibration actuator 10 is dropped, movablebody 20 makes contact with inner body part 522 only when the impact isapplied to vibration actuator 10 itself. That is, only when there is animpact, movable body 20 and inner body part 522 relatively move in arange between outer peripheral surface 20 a of movable body 20 and innerperipheral surface 522 a of inner body part 522, and the movement ofmovable body 20 is restricted by making contact with inner body part522.

In this manner, in vibration actuator 10, when an impact is applied tovibration actuator 10, movable body 20 is displaced and brought intocontact with the inner wall of the fixing body, without exerting animpact unlike in known vibration actuators. That is, coils 61 and 62 offixing body 50 are not damaged by an impact. In addition, with animpact, inner body part 522 restricts the movement of movable body 20,and thus elastic support parts 81 and 82 are not deformed by the impact.As a result, it is possible to eliminate failures such as a failure ofmovement of movable body 20 caused by deformation of elastic supportparts 81 and 82. In addition, since vibration actuator 10 causes movablebody 20 to reciprocate without sliding it on a shaft, the movement ofmovable body 20 does not generate a sound of sliding movement on theshaft as a matter of course.

In this manner, with vibration actuator 10, a preferable sensoryvibration with high vibration performance can be achieved whileproviding impact resistance.

Here, vibration actuator 10 is driven by an alternating current waveinput from the power supply part (for example, drive control unit 203illustrated in FIG. 16 and FIG. 17) to coils 61 and 62. That is, theenergization direction of coils 61 and 62 is cyclically switched, andthe thrust of the F direction on bottom portion 541 side of upper case54 and the thrust of the −F direction on bottom portion 561 side oflower case 56 alternately act on movable body 20. With thisconfiguration, movable body 20 vibrates in the vibration direction (thewinding axis direction orthogonal to the radial direction of coils 61and 62, or the magnetization direction of magnet 30).

In the following description, a driving principle of vibration actuator10 will be briefly described. In vibration actuator 10 of the presentembodiment, movable body 20 vibrates with respect to fixing body 50 byresonance frequency f_(r) [Hz] calculated from the following Equation(1), where m [kg] represents the mass of movable body 20, and K_(sp)represents the spring constant of the spring (elastic support parts 81and 82 of the spring).

$\begin{matrix}{\left\lbrack {{Equation}\mspace{14mu} 1} \right\rbrack\mspace{616mu}} & \; \\{f_{r} = {\frac{1}{2\pi}\sqrt{\frac{K_{sp}}{m}}}} & (1)\end{matrix}$

It can be said that movable body 20 constitutes the mass part of avibration model of a spring-mass system, and therefore, when analternating current wave of a frequency equal to resonance frequencyf_(r) of movable body 20 is input to coils 61 and 62, movable body 20 isbrought into a resonance state. That is, movable body 20 can beefficiently vibrated by inputting, from the power supply part to coils61 and 62, an alternating current wave of a frequency substantiallyequal to resonance frequency f_(r) of movable body 20.

An equation of motion and a circuit equation indicating a drivingprinciple of vibration actuator 10 are described below. Vibrationactuator 10 is driven by the equation of motion represented by thefollowing Equation (2) and the circuit equation represented by thefollowing Equation (3).

$\begin{matrix}{\left\lbrack {{Equation}\mspace{14mu} 2} \right\rbrack\mspace{619mu}} & \; \\{{m\frac{d^{2}{x(t)}}{dt^{2}}} = {{K_{f}{i(t)}} - {K_{sp}{x(t)}} - {D\frac{{dx}(t)}{dt}}}} & (2)\end{matrix}$

-   -   m: mass [kg]    -   x(t): displacement [m]    -   K_(f): thrust constant [N/A]    -   i(t): current [A]    -   K_(sp): spring constant [N/m]    -   D: attenuation coefficient [N/(m/s)]

$\begin{matrix}{\left\lbrack {{Equation}\mspace{14mu} 3} \right\rbrack\mspace{619mu}} & \; \\{{e(t)} = {{{Ri}(t)} + {\angle\frac{{di}(t)}{dt}} + {K_{e}\frac{{dx}(t)}{dt}}}} & (3)\end{matrix}$

-   -   e(t): voltage [V]    -   R: resistance [Ω]    -   L: inductance [H]    -   K_(e): counter electromotive force constant [V/(rad/s)]

That is, mass m [kg], displacement x(t) [m], thrust constant K_(f)[N/A], current i(t) [A], spring constant K_(sp) [N/m], attenuationcoefficient D [N/(m/s)] and the like in vibration actuator 10 can beappropriately changed within a range that satisfies Equation (2). Inaddition, voltage e(t) [V], resistance R [Ω], inductance L [H], andcounter electromotive force constant K_(e) [V/(rad/s)] can beappropriately changed within a range that satisfies Equation (3).

As described above, in vibration actuator 10, an efficiently largevibration output can be obtained when coils 61 and 62 are energized withan alternating current wave corresponding to the resonance frequencyf_(r) determined by the mass m of movable body 20 and the springconstant K_(sp) of elastic support parts 81 and 82 as leaf springs.

In addition, vibration actuator 10 is driven by a resonance phenomenonat the resonance frequency represented by Equation (1), satisfyingEquations (2) and (3). With this configuration, in vibration actuator10, the power that is consumed in a normal state is only the loss atattenuation part 72. It is possible to achieve driving with a low powerconsumption, or in other words, linear reciprocation of movable body 20with a low power consumption.

According to the present embodiment, since plate-shaped elastic supportparts 81 and 82 are disposed on the upper and lower side (in thevibration direction) of movable body 20, movable body 20 can be stablydriven in the vertical direction while efficiently distributing themagnetic flux of coils 61 and 62 from elastic support parts 81 and 82 onthe upper and lower side of magnet 30. With this configuration, as avibration motor, a vibration of high output can be achieved.

In addition, fixing body 50 includes coil holding part 52 having afunction of holding coils 61 and 62 and a function of protecting coils61 and 62 with respect to movable body 20. With this configuration, inthe case where vibration actuator 10 receives an impact, fixing body 50can sustain the impact and does not cause damage such as deformation inelastic support parts 81 and 82. In addition, for coils 61 and 62, theimpact is transmitted through resin inner body part 522, and thus highlyreliable vibration actuator 10 can be achieved while suppressing thedamage.

Embodiment 2

FIG. 14 is a longitudinal sectional view including a vibration actuatoraccording to Embodiment 2 of the present invention, and FIG. 15 is anexploded perspective view of a vibration actuator according toEmbodiment 2 of the present invention.

Vibration actuator 10A illustrated in FIG. 14 and FIG. 15 hassubstantially the same configuration as that of vibration actuator 10according to Embodiment 1 illustrated in FIG. 1 to FIG. 13, andvibration actuator 10A differs in coil holding part 52A in theconfiguration of vibration actuator 10. In vibration actuator 10A, thecomponents similar to those of vibration actuator 10 have similaroperations and effects. In the following description, the samecomponents are denoted by the same reference numerals, and reiterateddescriptions will be omitted.

That is, in vibration actuator 10A illustrated in FIG. 14 and FIG. 15,movable body 20A is housed in columnar fixing body 50A such that it canvibrate in the axis direction of the columnar shape. When movable body20A moves, vibration actuator 10A itself serves as a vibrating member.

Vibration actuator 10A includes movable body 20A including magnet 30 andmovable body cores 41 and 42, fixing body 50A including coils 61 and 62,and plate-shaped elastic support parts 81 and 82 that reciprocallysupport movable body 20A with respect to fixing body 50A.

At cylindrical coil holding part 52A disposed to surround the outerperiphery of magnet 30, vibration actuator 10A holds coils 61 and 62 onthe outer periphery side of coil holding part 52A.

Coil holding part 52A has a cylindrical shape, and includes recessedcoil attaching portion 522A that opens radially outward on the outercircumference side for disposing coils 61 and 62. Coil attaching portion522A is formed with ribs 528A, 528A and 526A protruding from the outersurface of the cylindrical part with a space therebetween in the axisdirection. Coils 61 and 62 disposed in coil attaching portion 522A arefixed in coil attaching portion by bonding or the like in the statewhere they are surrounded and sealed with electromagnetic shield part 58surrounding the outer peripheral surface of coil holding part 52A. It isto be noted that coil attaching portion 522A is formed as a recess thatopens radially outward and extends in the circumferential direction atthe outer periphery of coil holding part 52A, and thus also functions asa coil insertion part for insertion of coils 61 and 62 from the radiallyoutside.

Coils 61 and 62 are disposed by winding a coil line on coil holding part52A from the outside of coil holding part 52A. Thus, to maintaincylindrical coils 61 and 62, it can be assembled without using aself-welding line. In this manner, the same operations and effects asEmbodiment 1 can be achieved, and the cost of coils 61 and 62 can bereduced, and in turn, the cost of the entire vibration actuator 10A canbe reduced.

Examples of Electronic Apparatus

FIG. 16 and FIG. 17 are drawings illustrating an example of the mountingstate of vibration actuators 10 and 10A. FIG. 16 is a drawingillustrating an example in which vibration actuator 10 is mounted ingame controller GC, and FIG. 17 is a drawing illustrating an example inwhich vibration actuator 10 is mounted in mobile terminal M.

Game controller GC is, for example, connected to a game machine bodythrough wireless communication, and is held or grasped by a user. Here,game controller GC has a rectangular plate-shape, which is operated bythe user by holding it with hands at the left and right sides of gamecontroller GC.

Game controller GC uses the vibration to notify the user of a commandfrom the game machine body. It is to be noted that although notillustrated in the drawings, game controller GC includes, for example,an inputting operation part for a game machine body in addition to thecommand notification function.

Mobile terminal M is, for example, a mobile communication terminal suchas a mobile phone and a smartphone. Mobile terminal M uses the vibrationto notify the user of incoming calls from external communicationapparatuses, and achieves each function (for example, function of givinga sense of control and realism) of mobile terminal M.

As illustrated in FIG. 16 and FIG. 17, each of game controller GC andmobile terminal M includes communication unit 201, processing unit 202,drive control unit 203, and vibration actuators 10B, 10C and 10D servingas vibration actuator 10 serving as a driving part. It is to be notedthat in game controller GC, a plurality of vibration actuators 10B and10C are mounted.

In game controller GC and mobile terminal M, vibration actuators 10B,10C and 10D are mounted such that the main surface of the terminal andthe surface orthogonal to the vibration direction of vibration actuators10B, 10C and 10D, or in this case, the bottom surface of lower case 56are parallel to each other, for example. The main surface of theterminal is the surface that makes contact with the body surface of theuser, and in the present embodiment, the main surface of the terminalmeans a transmission surface that transmits the vibration by makingcontact with the body surface of the user.

To be more specific, in game controller GC, vibration actuators 10B and10C are mounted such that the vibration direction is orthogonal to thesurface where the fingertips, belly of the fingers, and equality of thehands of the operating user come into contact, or the surface where theoperation part is provided. In addition, in mobile terminal M, vibrationactuator 10D is mounted such that the display screen (touch panelsurface) and the vibration direction are orthogonal to each other. Withthis configuration, the vibration in the direction perpendicular to themain surfaces of game controller GC and mobile terminal M is transmittedto the user.

Communication unit 201, which is connected to an external communicationapparatus through wireless communication, receives a signal from thecommunication apparatus and outputs it to processing unit 202. For gamecontroller GC, the external communication apparatus is a game machinebody serving as an information communication terminal, and communicationis performed in accordance with a near field wireless communicationstandard such as Bluetooth (registered trademark). For mobile terminalM, the external communication apparatus is a base station, andcommunication is performed in accordance with a mobile communicationstandard, for example.

Processing unit 202 uses a conversion circuit part (omitted in thedrawing) to convert an input signal into a drive signal for drivingvibration actuators 10B, 10C and 10D, and outputs it to drive controlunit 203. It is to be noted that in mobile terminal M, processing unit202 generates a drive signal based on a signal input from variousfunctional parts (not illustrated, such as an operation part such as atouch panel) in addition to a signal input from communication unit 201.

Drive control unit 203 are connected to vibration actuators 10B, 10C and10D, and a circuit for driving vibration actuators 10B, 10C and 10D ismounted therein. Drive control unit 203 supplies a drive signal tovibration actuators 10B, 10C and 10D.

Vibration actuators 10B, 10C and 10D are driven in accordance with adrive signal from drive control unit 203. To be more specific, invibration actuators 10B, 10C and 10D, movable body 20 vibrates in adirection orthogonal to the main surfaces of game controller GC andmobile terminal M.

Movable body 20 may make contact with bottom portion 541 of upper case54 or bottom portion 561 of lower case 56 with a damper therebetweeneach time when movable body 20 vibrates. In this case, the impact of thevibration of movable body 20 on bottom portion 541 of upper case 54 orbottom portion 561 of lower case 56, that is, the impact on the housing,is directly transmitted as vibration to the user. In particular, in gamecontroller GC, with a plurality of vibration actuators 10B and 10C, oneor both of vibration actuators 10B and 10C can be simultaneously drivenin accordance with the input drive signal.

A vibration is transmitted to the body surface of the user that makescontact with game controller GC or mobile terminal M in the directionperpendicular to the body surface, and thus a sufficient sensoryvibration can be given to the user. Game controller GC can give thesensory vibration for to the user using one or both of vibrationactuators 10B and 10C, and thus can give a highly expressive vibrationsuch as strong and weak vibrations that are selectively applied.

The invention made by the inventor has been described in detail abovebased on the form of implementation. However, the invention is notlimited to the above form of implementation, and can be changed withinthe scope not deviating from the gist thereof.

In addition, for example, vibration actuators 10 and 10A according tothe embodiment of the present invention is suitably applicable to amobile apparatus (for example, a mobile information terminal such as atablet PC, a mobile game terminal, and a wearable terminal worn by theuser) other than game controller GC and mobile terminal M illustrated inthe embodiment. In addition, vibration actuators 10 and 10A according tothe embodiment of the present invention may be used as an exciter as avibration device that outputs a sound using vibration. An exciter, forexample, is a vibrating speaker that has the ability to produce sound bybringing the vibrating surface into contact with an object without usinga cone. In addition, vibration actuators 10 and 10A according to theembodiment of the present invention may be an exciter that cancels outand reduces external noise, such as road noise, by emitting sound. Inaddition, vibration actuators 10 and 10A according to the embodiment ofthe present invention may be used as a vibration generator. In additionto vibration actuators 10 and 10A of the present embodiment may also beused in electric beauty and hair care devices such as facial massagersthat require vibration.

This application is entitled to and claims the benefit of JapanesePatent Application No. 2018-159790 filed on Aug. 28, 2018, thedisclosure each of which including the specification, drawings andabstract is incorporated herein by reference in its entirety.

INDUSTRIAL APPLICABILITY

The vibration actuators of the embodiment of the present invention haveshock resistance and can output suitable sensory vibrations, and areuseful for use in electronic devices such as game machine terminals thatprovide vibrations to users, exciters serving as vibration devices thatemit sound, or mobile terminals.

REFERENCE SIGNS LIST

-   10, 10A, 10B, 10C, 10D Vibration actuator-   20, 20A Movable body-   20 a Outer peripheral surface-   22, 22A, 24, 24A Spring stopper-   30 Magnet-   30 a Surface-   30 b Rear surface-   41, 42 Movable body core (Yoke)-   50, 50A Fixing body-   52, 52A Coil holding part-   54 Upper case-   56 Lower case-   58 Electromagnetic shield part-   61, 62 Coil-   72, 72A Attenuation part-   73 Attaching portion-   81, 82 Elastic support part-   201 Communication unit-   202 Processing unit-   203 Drive control unit-   226, 246 Spring fixing part-   522 a Inner peripheral surface-   522 Inner body part (Coil protection wall part)-   522A Coil attaching portion-   524 Outer body part-   526 Center annular part-   541, 561 Bottom portion-   542, 562 Peripheral wall part-   722 Flange-   724 Rib (Pushing part)-   802 Inner periphery part-   804 Deformation arm-   806 Outer periphery part

What is claimed is:
 1. A vibration actuator comprising: a movable bodycomprising: a disk-shaped magnet; a pair of disk-shaped cores fixed onfront and rear surfaces of the disk-shaped magnet and each having anopening at a center thereof; a pair of leaf springs having asubstantially circular shape; and a pair of spring stopper weight partseach having one end positioned by joining the opening to be joined withone of the disk-shaped cores and having another end connected to acentral part of one of the leaf springs; and a fixing body comprising anannular coil and configured to support and accommodate therein themovable body such that the disk-shaped magnet, the disk-shaped cores andthe spring stopper weight parts are capable of vibrating in an axialdirection inside the annular coil.
 2. The vibration actuator accordingto claim 1, wherein the movable body is configured to vibrate based onthe following motion equation (Equation 1) and circuit equation(Equation 2), and wherein vibration of the movable body is determined bycalculating a spring constant of the leaf springs and a spring constantof a magnetic spring in a magnetic circuit including the disk-shapedmagnet and the annular coil. $\begin{matrix}{\left( {{Equation}\mspace{14mu} 1} \right)\mspace{644mu}} & \; \\{{m\frac{d^{2}{x(t)}}{dt^{2}}} = {{K_{f}{i(t)}} - {K_{sp}{x(t)}} - {D\frac{{dx}(t)}{dt}}}} & \;\end{matrix}$ m: mass [kg] x(t): displacement [m] K_(f): thrust constant[N/A] i(t): current [A] K_(sp): spring constant [N/m] D: attenuationcoefficient [N/(m/s)] $\begin{matrix}{\left( {{Equation}\mspace{14mu} 2} \right)\mspace{644mu}} & \; \\{{e(t)} = {{{Ri}(t)} + {\angle\frac{{di}(t)}{dt}} + {K_{e}\frac{{dx}(t)}{dt}}}} & \;\end{matrix}$ e(t): voltage [V] R: resistance [Ω] L: inductance [H]K_(e): counter electromotive force constant [V/(rad/s)]
 3. The vibrationactuator according to claim 1, wherein the movable body is configured tovibrate in an axial direction thereof by a thrust force generated byinteraction between a magnetic field of the disk-shaped magnet andcurrent flowing in the annular coil.
 4. The vibration actuator accordingto claim 1, wherein the annular coil includes a pair of coils would inopposite directions such that current flows in opposite directions uponenergization.
 5. The vibration actuator according to claim 1, wherein acentral position of the disk-shaped magnet in the axial direction is asubstantially same position as a central position of length in the axialdirection of the annular coil.
 6. The vibration actuator according toclaim 1, wherein each of the leaf springs is a planar, spiral springpartially having a damper.
 7. The vibration actuator according to claim1, wherein the leaf springs comprises a plurality of planar, spiralsprings and a plurality of dampers
 8. An electronic apparatus comprisingthe vibration actuator according to claim 1.